This invention concerns fire protection, and specifically is directed to a combination window shutter which allows some light to pass through when extended over a window, thus useful as a typical sun or privacy screen, but the shutter or shade being so constructed that when exposed to an exterior fire or firestorm while retracted it will automatically drop, covering the window, and prevent the passing of radiation sufficient to ignite most combustibles or cause the window glass to break. Further, it will protect the window from the impact of flying debris which is often created by a fire storm.
Other fire shutters have been constructed of a plurality of elongated slats interconnected together with a plurality of hinges to form a solid screen with virtually no possible passage of light, similar to the standard industrial roll-up door. They are not suitable for use as a sun screen. Further, they tend to be heavy and industrial in appearance. This invention, by allowing some light to pass through the shutter and also being much lighter in construction, can serve the combined purpose of a shade or privacy screen and a fire shutter. The means in which this is accomplished is that the spaces between slats, mesh screen wire, or other elements is sufficiently small so that they block the passage of a significant portion of the radiant waves. Further, the mechanism which automatically closes the shutter during a fire must be able to override manual operation. This can be done by means of a clutch arrangement which is disengaged (released) by a temperature actuated fusible link or other means at a temperature appropriately associated with an exterior fire, such as a wild fire, local vegetation or debris fire, or a close burning building, etc. The mechanism allows the shutter to close automatically (drop, in free fall) by gravity.
The key elements are the shutter with limited size openings and the clutch that can be disengaged at an appropriate temperature by fusible links or other means; the former constructed of slats strung on a cable or of mesh screen or other material, essentially fireproof or fire resistant, having openings small enough in at least one dimension to block much of the passage of radiant heat.
When used as a sun or privacy screen, the shutter would be raised and lowered manually by conventional means, such as chain lift, crank, gear driven mechanism, electric motor or other. The raising mechanisms and holding ratchets, brackets, drum on which the shutter is wound, tension spring and bearings are all of common design and use, and do not alone form a part of this invention. The details of these components may be modified from those shown to facilitate fabrication, reliability, cost, appearance or for other reasons.
Thus, the present invention provides a combination window shutter and fire protection screen which allows some light to pass through when extended over a window, thus serving as a typical sun or privacy screen, but which is so constructed that it can also automatically function as a barrier to radiant energy and flying debris generated by an exterior fire which might otherwise ignite combustibles, such as curtains and upholstered furniture just inside the window or break the glass and allow direct flame entrance. The mechanisms are simple and reliable, most having been used countless times in other applications. The uniqueness of this invention is in the nature of the shutter itself, which allows it to perform more than one function in an inexpensive, attractive and practical way, and the mechanism which allows it to be activated automatically during a fire.